The present disclosure relates to a power storage member state estimation device, a battery pack, an electric vehicle, a power storage device, and a power storage member state estimation method. In more detail, the present disclosure relates to a power storage member state estimation device that estimates the state of a power storage member, a battery pack, an electric vehicle, a power storage device, and a power storage member state estimation method.
In the related art, a technology that estimates the state of a power storage member based on the open circuit voltage (OCV) of the power storage member has been proposed. For example, a power storage system that calculates a charging state (SOC) according to an inter-terminal voltage, that is, the OCV, of a power storage device detected with a voltage sensor based on relational data of the inter-terminal voltage and the SOC created in advance is proposed in Japanese Unexamined Patent Application Publication No. 2013-158087. In such a power storage system, the SOC is calculated selectively using two relational data items according to the magnitude relationship between the integrated value of the discharge current value and the integrated value of the charge current value as the relational data.